1. Field of the Invention
The present invention relates to a switch suitable for use as a remote control switch for electrically operated rearview mirrors of a motor vehicle. More particularly, the invention relates to a switch having switch elements comprising a pressure-sensitive rubber sheet which becomes conductive only when and where it is pressed (hereinafter referred to as a "pressure-sensitive conductive rubber sheet" or a "rubber sheet".
Each of a pair of electrically operated rearview mirrors mounted on a door, a fender or the like, of a motor vehicle contains two electric motors, etc. in its driving section, said electric motors, etc. being controlled by means of a switch inside the vehicle so as to adjust the direction of inclination, horizontal or vertical, of each mirror. The switch for controlling the electrically operated rear view mirrors is required to have the functions of actuating each of said two electric motors of each mirror independently, and of changing the polarity of the electric power supplied thereto.
2. Description of the Prior Art
To meet the above requirements, Kiyoshi Nakayama, one of the inventors, has invented a switch which, as disclosed in Japanese Utility Model application No. Sho 56-71428, comprises a housing, an operating member disposed within said housing at a certain clearance from the inner walls of said housing, said operating member being adapted to swing from its neutral position in four directions meeting at right angles with one another, two switch elements disposed between said operating member and each of the four inner walls of said housing, each of said switch elements comprising a pair of electrodes and a pressure-sensitive conductive rubber sheet disposed therebetween, said switch elements being adapted to change the polarity of the electric power supply.
However, the disclosed switch has a deep shape and cannot be made small because the operating member is swingably disposed within the housing and the switch elements are disposed between the operating member and the four inner walls of the housing. Also, the switch is not very easy to assemble. Furthermore, it does not give a reassuring feeing of use because the operating member has almost no stroke and does not click at all.
U.S. Pat. No. 4,324,472, K. Terada et al. This patent discloses a camera switch for an electrical shutter which can be operated with a soft touch. The switch is made up of an electrode base formed of a flexible printed circuit board, a pressure-sensitive conductive rubber sheet element overlying the printed circuits, and a button with a plurality of projections on its bottom surface. By pressing the button the sheet element is selectively compressed to close the shutter circuit.
U.S. Pat. No. 4,029,915, S. Ojima, describes a keyboard for an electronic computer which keyboard includes a printed circuit board, a contact holder formed of a flexible insulating film and having movable contacts, and keys perpendicular to the printed circuit board but supported to be tilted in a plurality of directions. Four types of switch elements can be selectively actuated by pressing the keys. This structure assumes that any given key is properly tilted when it is depressed.
U.S. Pat. No. 2,857,485, R. Brooks, discloses a multi-position electric switch which through an operating lever, manipulates a wobble disc electrical contact.
The prior art patents do not give any consideration to the problems which arise when a key is incorrectly tilted, as when the corner of a key is depressed, or tilted obliquely, or when two respective switch elements simultaneously could be closed to an ON state.